AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 915 PM EST MON JAN 17 2000 ZFP DISC: PLAN TO REMOVE ALL POPS FROM FIRST PERIOD AS REGIONAL RADARS INDICATE THAT THE PRECIPITATION IN GA HAS RETREATED TO THE FAR NE PORTION OF OUR CWFA. WITH JUST TRACE AMOUNTS EXPECTED THERE...WILL JUST KEEP SPRINKLES IN FORECAST FOR ZONES N AND E OF ABY AND MOULTRIE THROUGH MIDNIGHT. OF THE MODEL QPF FIELDS...ONLY THE NGM SPITS OUT ANY PRECIP OVER OUR AREA TONIGHT. THAT MODEL DEPICTS A BAND OF .01 TO .06 ACROSS OUR GA ZONES...BUT THIS APPEARS TO BE DISPLACED ABOUT 100 MI TOO FAR TO THE S AND W. SATELLITE PIX SHOWING ST DECK GRADUALLY SHIFTING TO THE E AS PROGGED BY THE LATEST RUC AND 18Z ETA. OTHER CLOUDS MOVING S INTO CENTRAL AL WILL ARRIVE BEFORE MORNING. IN THE INTERIM...MOSTLY CLEAR SKIES WILL PREVAIL ACROSS SW PORTIONS OF THE CWFA WITH DECREASING CLOUDINESS TREND FURTHER E. WITH THE AREA IN A COL...LIGHT WINDS WILL ALLOW US TO RADIATE A BIT AND WILL INSERT PATCHY FOG ALL ZONES. 00Z TEMPS AND DEW POINTS WERE RUNNING A GOOD 5 TO 7 DEGREES ABOVE GUIDANCE ACROSS THE BOARD. NEVERTHELESS...WITH AFOREMENTIONED RADIATIONAL COOLING ANTICIPATED...WILL ONLY NUDGE MIN TEMP FORECAST UP ONE CATEGORY. MARINE: VARIOUS MODEL SURFACE WIND FIELDS OVER THE GULF ARE FAIRLY DIVERGENT FOR TONIGHT...BUT SPEEDS WILL BE INSIGNIFICANT ANYWAY WITH MOST BUOYS AND CMAN STATIONS REPORTING 5 KT OR LESS. WILL JUST GO WITH VARIABLE DIR FOR E LEG AND LIGHT WEST FROM AQQ W. EXTENDED: UPDATED EXTENDED/OUTLOOK PORTIONS OF ZFP AND CWF TO ACCOUNT FOR POPS ASSOCIATED WITH FROPA THAT OCCURS DURING THE PERIOD. BASED ON INSPECTION OF AVN...MRF...UKMET AND NCEP MANUAL PROGS...IT LOOKS LIKE THE BEST CHANCE FOR PRECIP WITH NEXT SYSTEM WILL BE WED NIGHT INTO THU WITH FROPA EARLY THU. HIGH PRESSURE BUILDS IN FOR A DRY FORECAST ON FRI. THANKS FOR COORD JAX. .TLH... AL...NONE. GA...NONE. FL...NONE. MAW fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 316 PM CST MON JAN 17 2000 MAIN FORECAST CHALLENGES ARE CLOUDS TONIGHT AND POPS IN LATER PERIODS. 12Z UA MAP ANALYSIS SHOWED MAIN ACTION STILL TO THE NORTH WHERE HEIGHT RISE/FALL/RISE TRIPLET WAS LOCATED IN PAC NW/NORTHERN PLAINS/NORTHEAST CONUS RESPECTIVELY FROM 500 MB DOWN AND LITTLE APPRECIABLE CHANGES ELSEWHERE. WARMEST AIR CONTINUES TO BE FOUND FROM DDC CWA SOUTH AND SOUTHWEST. 850 MB MOIST TONGUE WAS JUST EAST OF AREA WITH 30 TD DEPRESSION FROM DDC RAOB. LOW CLOUDINESS HAS ALL BUT ENDED OVER CWA AND TEMPS HAVE RECOVERED NICELY. 19Z SFC MAP PUT FRONTAL BOUNDARY FROM ROUGHLY CAO TO CDS TO JLN BUT 40+ F TDS LURK IN NORTHERN OKLAHOMA. NO CLEAR WINNER FOUND IN MODEL INITIALIZATION WITH ALL, AS EXPECTED, NOT HANDLING BOUNDARY LAYER MOISTURE WELL. FIRST CONCERN IS ANY RETURN OF LOW CLOUDS TONIGHT. SEE LITTLE CHANGE IN AIRMASS AND NEAR SATURATED CONDITIONS AGAIN SEEM POSSIBLE WITH LIGHT CAA. NGM AND ETA KEEP 925 MB RH LEVELS AT 50 AND 70 PERCENT THROUGH THE NIGHT WITH MESOETA AND RUC ONLY SLIGHTLY HIGHER THAN ETA. ISENTROPIC LIFT IS WEAKER THAN YESTERDAY AND GIVEN A LACK OF LOW CEILINGS ATTM, AS WAS SEEN YESTERDAY, AM NOT CONFIDENT IN RETURN OF LOW CLOUDS. CONSIDERABLE CIRRUS SHOULD CONTINUE OVERHEAD AND MOSTLY CLOUDY WORDING SHOULD HANDLE THINGS FAIRLY WELL IF SOME STRATUS DOES FORM. SWING SHIFT WILL HAVE TO MONITOR THIS CLOSELY. SOUTHERN STREAM ENERGY APPROACHES TUESDAY. SPEED OF VORT MAX AND LOCATION AND STRENGTH OF SFC LOW SPINUP IS IN QUESTION WITH FAST FLOW AND AFOREMENTIONED BOUNDARY LAYER DIFFICULTY. SEE NO REASON TO PULL SLIGHT POP GOING IN THE WEST AND WILL SHOTGUN SMALL POPS OVER ALL AREAS TUES NIGHT GIVEN THIS UNCERTAINTY. THINK WARMER TEMPS WILL BE REALIZED WEDNESDAY WITH LOWER TROPOSPHERIC MOISTURE, SOME DOWNSLOPE, AND SUBSIDENCE BEHIND WAVE. HAVE MOSTLY STUCK CLOSE TO FWC GUIDANCE WITH FAN BEING CONSISTENTLY TOO HIGH WITH TEMPS OVER THE PAST FEW DAYS. EXTENDED DISCUSSION... MRF AND CANADIAN SPECTRAL IN FAIR AGREEMENT THROUGH SATURDAY EVENING WHILE ECMWF IS A BIT SLOWER WITH ENERGY MOVING THROUGH THE SOUTHERN BRANCH OF THE WESTERLIES. ECMWF ALSO KEEPS THE SOUTHERN BRANCH TROF ABOUT 10 TO 15 DEGREES FARTHER WEST OVER THE EASTERN PACIFIC. ALL MODELS DO MAINTAIN THE SPLIT IN THE UPPER FLOW NEAR THE PACIFIC NORTHWEST COAST WITH NO MAJOR CHANGES IN THE GENERAL CIRCULATION PATTERN. TIMING OF WAVES THROUGH THIS REGIME WILL BE NEARLY IMPOSSIBLE AND CONFIDENCE REMAINS VERY LOW IN LATE PERIODS OF THE FORECAST. SURFACE LOWS FORECAST IN THE HIGH PLAINS REGION ON THURSDAY AND AGAIN ON MONDAY WILL LIKELY BE FARTHER SOUTH ALONG THE EDGE OF THE COLD AIR THAN ANY OF THE MODELS FORECAST. AS EACH OF THESE WAVES MOVES ACROSS THE CHANCE FOR CLOUD AND POSSIBLY EVEN SOME LIGHT DRIZZLE OR FOG IN UPSLOPE EXISTS BUT WITH TIMING OF THE WAVES IN SERIOUS DOUBT WILL NOT MAKE MAJOR CHANGES. SINCE CANADIAN AND MRF AGREE ON THE FIRST WAVE WILL GO AHEAD WITH SOME CLOUD AND MODERATED TEMPERATURES FOR THURSDAY NIGHT INTO FRIDAY BUT WILL NOT JUMP ON CHANCES FOR PRECIPITATION. PRELIMINARY GUIDANCE FOR COORDINATION ONLY. OFFICIAL FORECASTS ARE CONTAINED WITHIN THE DODGE CITY ZONE FORECAST. DDC 033/048 032/052 030 003 GCK 032/047 032/053 028 0-3 EHA 032/049 033/056 027 023 LBL 033/048 032/055 029 023 HYS 029/046 031/049 027 003 P28 035/049 034/052 033 003 .DDC...NONE. POAGE/JOHNSON ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 210 PM CST MON JAN 17 2000 FORECAST CONCERNS: -RA/FOG/DZ/CLDS EARLY...CLDS/TEMPS AND PRECIP CHC ON WED. -RA/DZ AND FOG PERSISTED THRU MOST OF THE DAY. BREAKS IN THE OVERCAST & S WNDS IN EXT SW MO CAUSED TEMPS TO RISE INTO THE 60S. LARGE TEMPS GRADIENT DEVELOP TDY OVR SW MO... WHERE TEMPS WERE 20 DEGREES DIFFERENT FROM PINEVILLE TO SPRINGFIELD MO. OVR AIZ/VIH TEMPS STILL WERE IN THE 30S. SHORT TERM MODELS ARE INDICATING MORE CLD CVR FOR TUE AS ANOTHER IN THE SERIES OF SHORT WAVES MOVES FROM S CA ACROSS THE ROCKIES INTO THE AREA BY TUE AFTN. IN THE SHORT TERM WILL NEED TO ADDRESS THE LATEST SAT LOOP TO SEE IF DRIER AIR WILL PUSH INTO SE KS OVERNIGHT. LATEST RUC SHOWING BULK OF THE DEEP MOISTURE MOVING TO THE E BY 00Z. HOWEVER WITH WEAK SFC WND FIELD OVERNIGHT AND ABUNDANT LOW LEVEL MOISTURE... BELIEVE FOG/OVERCAST SKIES WILL HOLD ON THRU TUE MORNING. BUT AS LOW CLDS/FOG AND DRIZZLE SLOWLY ERODE TUE MORNING...IT WILL BE FOLLOWED BY A PROGRESSIVE AMT OF MID/HIGH LEVEL MOISTURE. SO WORDING FOR TUE ZONES WILL BE MORNING FG/DZ WITH MOSTLY CLOUDY/PARTLY SUNNY THROUGH THE AFTN. N/NE WND FLOW WILL BECOME S/SE ON TUE NIGHT INTO WED IN RESPONSE TO NEXT SHORT WAVE ACROSS THE NORTHERN PLAINS. MODELS ARE INDICATING DEEPER MOISTURE ASSOCIATED WITH WED SYSTEM...ALONG WITH A STRONG WAA/ISENTROPIC LIFT PATTERN ACROSS FA. 1000/850H THICKNESS VALUES INDICATING A SHALLOW LAYER OF COLD AIR AT THE BEGINNING OF WED SYSTEM. NGM IS THE COOLEST WITH ETA THE WARMEST. HOWEVER CAN NOT RULE OUT A SHORT PERIOD OF FREEZING PRECIPITATION BEFORE THE WARMER AIR MOVES IN... ESPECIALLY IN N FA. A MUCH STRONGER SHORT WAVE & ASSOCIATED CLD FRONT WILL MOVE THRU WED NIGHT INTO THU. THICKNESSES DROP OFF RAPIDLY...PLUS 50-60 KTS AT THE 70/85H LEVEL. THIS MAY SET THE STAGE FOR FRI/FRI NIGHT SYSTEM WHICH MAY BE IN THE FORM OF SN. WILL WAIT AND SEE. EXTENDED PERIOD CONTINUES TO BECOME MORE INTERESTING. LONGER RANGE MODELS ARE NOW MORE IN LINE WITH YESTERDAYS MRF SOLUTION BRING A STRONGER SHORT WAVE TROF IN THE MID PART OF THE U.S. BY FRI. THERE ARE SOME DIFFERENCES IN THE SFC FRONT/LOW AND STRENGTH OF THE SYSTEM...HOWEVER THE MAIN UPPER LEVEL PATTERN DOES CHANGE AS THE MAIN JET MOVES FURTHER SOUTH ACROSS THE CENTRAL PART OF THE COUNTY. WILL LEAN TOWARD THE FASTER/PROGRESSIVE MRF SOLUTION THIS PACKAGE. WITH THIS IN MIND WILL CONTINUE THE TREND OF LIGHT PRECIPITATION ON FRI...WITH MUCH COLDER CONDITIONS ON SAT. BY THE BEGINNING OF NEXT WEEK...A LONG POSITIVE TILTED TROF DEVELOPS ACROSS THE CENTRAL U.S. WHICH WILL GIVE AN EVEN BETTER CHANCE OF PRECIPITATION BY MON/TUE/WED. PRELIM CCF NUMBERS ARE FOR COORDINATION ONLY... SGF EC 038/048 028/048 022 251--2 JLN EC 035/050 031/051 024 25---3 UNO EC 032/050 027/048 025 252--2 VIH EC 034/042 025/047 019 253--2 .SGF...NONE. JLT mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 1009 AM CST MON JAN 17 2000 SFC FRONT LOCATED FROM NEAR JOPLIN SE TO KIMBERLING CITY AREA. NORTH & E OF FRONT FOG/-RA/DZ WAS OCCURRING WITH TEMPS IN THE 30S/40S. S/SW OF FRONT TEMPS RISE INTO THE 50S WITH BREAKS IN THE OVERCAST. ALSO NO FOG/DZ/-RA WITH VISIBILITIES AROUND 7SM OR GREATER. LATEST RUC HAS SFC WNDS FROM SE/S DIRECTION THRU 18Z... WITH LAYER RH FIELDS SLOWLY DECREASING FROM W TO E. RADAR RETURNS STILL INDICATING -RA/DZ BUT BULK OF PRECIPITATION N/E OF FA. 12Z UPPER AIR ANALYSIS STILL INDICATING WAA THRU AFTN...WILL ADJUST TEMPS... ALONG WITH -RA/DZ CHANCES AS DEEPER MOISTURE REMAINING N/E OF FA. NO OTHER CHANGES FOR EXTENDED ATTM... BUT MAY ISSUE A SPS FOR WINTER PRECIPITATION CHANGES FOR FRI/FRI NIGHT. JLT mo MOJAVE DESERT/SOUTHERN GREAT BASIN AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAS VEGAS NV 825 PM PST MON JAN 17 2000 SYNOPSIS...SUBTROPICAL MOISTURE WILL CONTINUE TO SPREAD OVER THE REGION WITH CONSIDERABLE CLOUDINESS THROUGH WEDNESDAY. A WEATHER SYSTEM WILL INCREASE THE CHANCES OF PRECIPITATION TONIGHT AND TUESDAY AS IT MOVES ACROSS THE AREA. TEMPERATURES WILL CONTINUE WELL ABOVE NORMAL THROUGH THE PERIOD. DISCUSSION...EASTERN PACIFIC TROUGH REMAINS ANCHORED VICINITY 40N/135W THIS EVENING. IN ADVANCE OF THIS FEATURE...BROAD SOUTHWEST FLOW OF DEEP SUBTROPICAL MOISTURE CONTINUES TO INFLUENCE THE WESTERN U.S.. PRECIPITABLE WATER VALUES CONTINUE TO INCREASE WITH DRA SOUNDING SHOWING 0.80 INCHES AT 00Z (AS COMPARED TO AROUND ONE HALF AN INCH AT 00Z MON). OF NOTE ARE SEVERAL IMBEDDED SHORT WAVES IN THIS FLOW. THE FIRST OF WHICH (ANALYZED BY BOTH THE 00Z ETA AND RUC) IS ALONG THE SOUTHERN CALIFORNIA COAST WITH A MORE SIGNIFICANT SHORT WAVE UPSTREAM VICINITY 30N/130W. MODEST UPWARD MOTION IN ADVANCE OF THE FIRST SHORT WAVE RESPONSIBLE FOR THE INCREASE IN LIGHT PRECIPITATION ACROSS SOUTHERN CALIFORNIA AND SOUTHERN NEVADA THIS EVENING. NEXT MODEST SHOT OF OMEGA AND UPWARD FORCING ARRIVES EARLY TUESDAY MORNING (12-18Z) AND WILL AFFECT AREAS FARTHER NORTH AS WELL. CURRENT FORECAST HAS THIS COVERED WELL WITH MENTION OF ISOLATED TO SCATTERED SHOWERS FOR MOST ZONES TONIGHT INTO TUESDAY AND NOT PLANNING ANY UPDATES THIS EVENING. WITH THE ADDITIONAL UPWARD FORCING AND A STRONG OROGRAPHIC COMPONENT OVER THE SIERRA...POSSIBILITY OF LIGHT ACCUMULATIONS OF SNOW ON EASTERN SLOPES STILL NOT OUT OF THE QUESTION EARLY ON TUESDAY. 00Z ETA AND NGM SHOW CONSIDERABLE DRYING OCCURRING FROM W TO E TUESDAY AFTERNOON AND EVENING WITH THE PASSAGE OF THE SECOND SHORT WAVE. IF THIS IS CORRECT...CURRENT FORECAST MAY BE HOLDING ONTO PRECIPITATION CHANCES AND CLOUDINESS A BIT TOO LONG. WILL LET NEXT SHIFT TAKE A CLOSER LOOK AT THIS WHEN THE FULL MODEL SUITE IS AVAILABLE. NEMETH .LAS...NONE. nv AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1050 AM CST MON JAN 17 2000 MADE SOME RECENT CHANGES IN ZONES FOR WRN HALF OF THE CWA. MAINLY TO PLACE MORE CLD CVR TO TO THICK CIRRUS. HAVE ONLY HAD A CHC TO LOOK AT 12Z RUC/ETA THIS MRNG AND ONCE AGAIN VRY DISSAPPOINTED THAT THE DARN MDLS /EXCEPT NGM/ DO NOT EVEN KNOW THE HI CLDS ARE THERE. REGARDLESS...FCST SOUNDINGS SHOW QUITE A BIT OF WARM AIR ALF...BUT SOME DIFFICULTY IN ERODING SHALLOW COLD AIR. 16Z SFC ANLYS ALSO SHOWING WIND SHIFTS MUCH LATER THAN IN PRVS FCSTS. RECENT CALL FM LOCAL RADIO STATION IN SPENCER HAS INDICATED SOME SPOTTY REPORTS OF FREEZING DRIZZLE. WL HOLD OFF UPDATING ERN CWA TIL NOON TO LEAVE IN MENTION OF PCPN IN THE PKG FOR ANOTHER HOUR OR SO TO PLAY IT SAFE. ALSO WL NEED TO TAKE INTO THAT LACK OF FRONTAL PASSAGE MAY HAMPER EXPECTED HI TEMPS. .FSD...NONE BR sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 255 AM CST TUE JAN 18 2000 FORECAST ISSUES ARE THE CLEARING TRENDS IN THE SHORT TERM PLUS PATTERN CHANGES AND ASSOCIATED WEATHER IN THE LATER PERIODS. THE EARLY MORNING SURFACE ANALYSIS SHOWED THE COLD FRONT JUST SOUTH OF THE FA...EXTENDING BACK TO THE WEST. RADAR REVEALED SHOWERY ECHOES MOVING EAST OF FORECAST AREA...WITH PATCHY DRIZZLE/FREEZING DRIZZLE STILL LINGERING MAINLY IN THE EAST THIRD OF FA. CEILINGS AROUND OR BELOW 1K FT EXTEND AS FAR WEST AS KANSAS CITY. 18/00Z KSGF SOUNDING SHOWED FRONTAL INVERSION THROUGH 800MB. THE 18/00Z 850MB ANALYSIS SHOWED SHARP DEWPOINT DEPRESSION CONTRAST ON EACH SIDE OF THE 850MB BOUNDARY IN THE PLAINS. 18/06Z RUC ADVECTS THIS DRIER AIR INTO FA BY NOON. THIS APPEARS OPTIMISTIC AT BEST GIVEN LITTLE EAST MOVEMENT OF THIS CLEAR AREA SINCE 18/00Z. IN ADDITION...HIGHER CLOUDS CONTINUE TO STREAM INTO PLAINS AND FA FROM PACIFIC MOISTURE PLUME. ZONE WORDING WILL BE MORE PESSIMISTIC THAN CURRENT EDITION. WILL USE AVN FOR LATER PERIODS PER NCEP DISCUSSION. WEAK WARM FRONT AND ASSOCIATED CLOUDS RETURN WEDNESDAY. I290K UPGLIDE BY END OF THE DAY AND SIGNIFICANT RH WOULD SUPPORT SOME LIGHT PRECIP. COLD SIDE OF 1000-850MB CRITICAL THICKNESS LINGERS ACROSS NORTHEAST SECTIONS OF FA. WILL MENTION SPRINKLES &/OR FLURRIES POSSIBLE ACCORDINGLY. AS THIS SURFACE LOW MOVES THROUGH FA WEDNESDAY NIGHT PRESSURE GRADIENT TIGHTENS WITH NEXT COLD AIR PLUNGE...MAKING FOR A VERY RAW NIGHT AND EARLY PART OF THE DAY THURSDAY. ABOUT 24 HOURS OF CLEARING CAN BE EXPECTED BEFORE NEXT WEATHER SYSTEM APPROACHES FRIDAY. .PAH...NONE PAUL W ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BALTIMORE/WASHINGTON 300 AM EST TUE JAN 18 2000 07Z SURFACE ANALYSIS SHOWING WEAK LOW PRESSURE CENTER OVER THE TENNESSEE VALLEY... WHICH MODELS ALL FORECAST TO MOVE WELL TO THE SOUTH OF THE AREA AS THE DAY GOES ON. KLWX SHOWING SOME LIGHT RETURNS OVER THE FAR SOUTHWESTERN PORTION OF THE AREA... BUT DOUBTFUL IF ANYTHING IS HITTING THE GROUND. KRLX/KFCX RADARS AND SURFACE OBS INDICATE SOME LIGHT SNOW FALLING OVER SOUTHERN HALF OF WVA AND FAR SOUTHWESTERN VA. WEAK LOW AND ASSOCIATED SURFACE TROUGH PROGGED BY ETA/NGM/AVN TO MOVE ACROSS THE CAROLINAS TODAY. MAIN DYNAMIC LIFT WITH THE SYSTEM SHOULD BE OVER THE AREA THIS MORNING... WHILE Q-G FIELDS INDICATE SOME UPWARD MOTION ACROSS THE AREA THROUGH THE FIRST HALF OF THE AFTERNOON. 00Z IAD SOUNDING EXTREMELY DRY IN THE LOWER TROP... AND 00Z ETA AND 03Z RUC SHOW A SURGE OF LOW LEVEL MOISTURE MAKING ITS WAY UP ONLY AS FAR AS CHO AREA. EXTRAPOLATION OF HIGHER RETURNS FROM KRLX RADAR SHOW SOME LIGHT SNOW HEADED FOR FAR SW CORNER OF CWA... AND ETA/NGM/RUC ALL INDICATE AROUND 0.05 INCH OF LIQUID PRECIP FOR THE AREA. WILL GO WITH LIGHT SNOW LIKELY OVER NELSON/AUGUSTA/HIGHLAND COUNTIES TODAY... AND MENTION LESS THAN AN INCH OF ACCUMULATION PER QPF. FOR THE REST OF THE AREA.. LACK OF LOW LEVEL MOISTURE SHOULD KEEP SNOW AT BAY. EXPECTING MIXTURE OF MID/HIGH LEVEL CLOUDS AND THE POSSIBILITY OF A FLURRY. ETA/NGM BOTH AGREE ON KEEPING CLOUDS ACROSS THE AREA TONIGHT... BUT WITH NORTHWEST FLOW DEVELOPING ON THE BACK SIDE OF THE LOW EXPECT DOWNSLOPE TO SCOUR CLOUDS OUT A LITTLE QUICKER THAN MODELS INDICATE. WILL BE A LITTLE MORE OPTIMISTIC WITH COVERAGE TONIGHT... AND WILL LIKELY UNDERCUT MOS TEMPS ACCORDINGLY. ONLY DEVIATION WILL BE A CONTINUING MENTION OF FLURRIES OR LIGHT SNOW SHOWERS FOR THE FAR NW PORTION OF THE AREA. EXTENDED FORECAST LOOKING A LITTLE MORE INTERESTING... WITH LOW PRESSURE SYSTEM POISED TO CROSS THE AREA ON THURSDAY. MOISTURE WILL AGAIN BE A QUESTION.. AND MODELS ARE STILL TRYING TO COME TO AN AGREEMENT ON EXACT PATH. WILL LEAVE EXTENDED FORECAST ALONE... AND CHANCE OF SNOW MENTIONED LATE WED NIGHT AND THURSDAY LOOKS GOOD FOR NOW. .LWX...NONE. MARGRAF! md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 834 PM CST MON JAN 17 2000 BACK EDGE OF LOW CLOUDINESS PROGRESSING VERY SLOWLY EASTWARD (9 KTS) THIS EVENING AND NOW NEARING A KAXN TO KFRM LINE. LIGHT FREEZING DRIZZLE CONTINUES WITH THE LOW CLOUDINESS. THE MASS WILL GET SHOVED EAST AND SOUTH DURING THE NIGHT AS A COLD FRONT CURRENTLY PROGRESSING ACROSS NW MN MOVES SE ACROSS THE STATE. 21Z RUC HAS A GOOD HANDLE ON THE SURFACE FRONT AND EXPECT IT HERE AT KMPX AROUND 09Z. WILL ADJUST THE WORDING TO KEEP THE CLOUDS AND FREEZING DRIZZLE LINGERING LONGER IN FAR EASTERN MN AND WEST CENTRAL WI. TEMPERATURES AND WINDS LOOK GOOD. .MSP...NONE. HILTBRAND mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 906 PM EST MON JAN 17 2000 LATEST RUC AND MESOETA INDICATE THAT IT WILL PROBABLY BE CLOSER TO DAWN BEFORE PRECIP WILL COMMENCE...ALTHOUGH THE FIRST BATCH OF LIGHT RAIN OVER N GEORGIA WAS MOVG STEADILY ESE AND OBSERVATIONS DO SHOW SOME -RA IN THAT REGION. PLAN TO CONTINUE CHCY POPS...MAINLY LATE OR TOWARD SUNRISE IN SE GEORGIA ZONES. SFC DEW POINT ANALYSIS FROM 01Z INDICATES SHARPEST TRANSISTION REGION ACROSS NW COLLETON-DORCHESTER- BERKELEY ZONES. THESE NWRN FRINGES ARE OUR ONLY CONCERN AREAS FOR PRECIP POSSIBLY STARTING AS A RAIN/SLEET MIX. GIVEN THE MUCH LOWER SFC DEWPOINTS OVER THE BORDERING COUNTIES IN CAE FA...DO NOT EXPECT ANY SIGNIFICANT PROBLEMS. PER COORD WITH CAE...WILL MENTION PRECIP POSSIBLY STARTING AS RAIN/SLEET MIX AT THE ONSET IN THE FOREMENTIONED ZONES. WILL LIKELY LOWER MINIMUMS A CAT IN S CAROLINA ZONES GIVEN DELAY IN CLOUD COVER AND LOW DEW POINTS. LOW TEMPERATURES IN GEORGIA ZONES ALSO A CHALLENGE BUT LIKELY TO REMAIN STEADY OR SLOWLY RISE LATER TONIGHT. THANKS FOR THE COORD ILM/CAE. CWF...WINDS STARTING TO VEER SLOWLY ESP SRN WATERS AND DECREASING A LITTLE IN ALL LOCATIONS AS WK HI SLIDES E. ONLY NEED TO MAKE SOME ADJUSTMENTS ON THIS PKG TO MATCH LATEST OBS. TREND LOOKS GOOD. .CHS... SC...NONE. GA...NONE. RVT/MJR sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE COLUMBIA SC 815 PM EST MON JAN 17 2000 WEDGE OF COLD DRY AIR AT THE SURFACE CONTINUES OVER THE CAROLINAS. NORTH CAROLINA DEWPOINTS ARE IN THE SINGLE DIGITS WHILE THE AIR IS MODIFIED IN SOUTH CAROLINA. CAE DEWPOINT HAS CREPT UP TO 22. GOOD MOISTURE GRADIENT SOUTHERN PART OF AREA. AGS DEWPOINT 32 AND CHS 36. NORTHEAST FLOW FROM NORTH CAROLINA SHOULD KEEP DEWPOINTS 18-22 MOST OF CAE CWA TONIGHT BUT THEY SHOULD INCREASE TO THE MIDDLE TO UPPER 20S IN THE MORNING NEAR DAYBREAK WHEN THE PRECIPITATION IS EXPECTED TO BEGIN. MODEL FORECAST RAOBS FOR CAE SHOW SURFACE BASED FREEZING LAYER ABOUT 3 THSD FT 6-8AM IN THE MORNING. BUT 4-6 THSD FT TEMPERATURES ARE +5/+6C WHERE MUCH OF THE PRECIP SHOULD BE DEVELOPING. THE SURFACE BASED FREEZING LAYER SHOULD COOL CONDITIONS AT THE SURFACE TO NEAR FREEZING WHERE RAIN COULD FREEZE TO MAINLY METALLIC SURFACES AND TREE LIMBS ALTHOUGH SOME PATCHY ICE IS POSSIBLE ON BRIDGES AND OVERPASSES. TEMPERATURES IN THIS COLD LAYER SHOULD BE ON THE ORDER OF -2/-5C. THIS PROBABLY WILL NOT BE COLD ENOUGH THE FREEZE MOST OF THE RAIN DROPS AS THEY FALL. SO MAIN THREAT OF WINTER WEATHER NEAR CAE SHOULD BE FROM FREEZING RAIN. CHECKED FORECAST RAOBS FOR AREAS NORTH OF CAE UP TOWARD THE NORTH CAROLINA STATE LINE. THEY WERE GIVING COLDER TEMPERATURES AT 4-6 THSD FT WITH +2/+3C. THE COLD LOW LAYER MAY FREEZE MORE RAIN DROPS UP THERE GIVING THEM MORE SLEET. LOOKING AT THE PROBABILITY OF PRECIPITATION DEVELOPING AND REACHING THE SURFACE IN THIS DRY AIR LAYER...THE RUC TIME SECTION SHOWS GOOD CONVERGENCE IN THE AGEOSTROPHIC FLOW OVER THE AREA OVERNIGHT THROUGH 09Z. A PROCEDURE USED TO DETECT COLD FRONTS ALOFT INDICATED THE DEVELOPMENT OF THIS FEATURE AT 600MB BY 00Z LOWERING TO 700MB BY 06Z AND AN INCREASE IN LOW LAYER MOISTURE THROUGH 09Z. THE PRESENCE OF A COLD FRONT ALOFT SHOULD ENHANCE THE CHANCES FOR PRECIPITATION. OTHER FEATURES THAT SHOULD ENHANCE PRECIP INCLUDE AN H8 40-50KT JET MOVING OVER THE AREA. H8 WINDS ARE SOUTHWEST OVERNIGHT BUT BECOME WEST AFTER 12Z. MODEL H7 BRINGS AN AREA OF UPWARD LIFT OVER THE AREA 06Z-18Z AND H5 BRINGS A WEAK SHORT WAVE THROUGH 06Z-12Z. THE 290K LEVEL INDICATES GOOD ISENTROPIC LIFT LATE TONIGHT AND ON TUESDAY AS WELL. SO FEEL THERE IS A PRETTY GOOD CHANCE OF PRECIP DEVELOPING BY DAYBREAK TUESDAY AND WILL CONTINUE WINTER WEATHER ADVISORY IN SAME AREAS FOR MAINLY FREEZING RAIN. WILL DOWNPLAY THREAT OF SLEET EXCEPT IN AREAS TO THE NORTH OF CAE. OTHERWISE...THE LOW TEMPERATURES AND POPS SOUND OK. .CAE...WINTER WEATHER ADVISORY LATE TONIGHT AND TUESDAY MORNING. SCZ015-016-018-020>022-025>031-036>037. TTH sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1030 AM CST TUE JAN 18 2000 ...FORECAST PROBLEMS ARE TEMPERATURES THIS AFTERNOON AND SNOW CHANCES WEDNESDAY... 16Z SURFACE TEMPERATURES ARE BELOW 00Z FWC SPOT VALUES AND 00Z ETA SURFACE TEMPERATURE VALUES ACROSS CWA. 16Z SURFACE TEMPERATURES FROM LATEST RUC ARE COLDER THAN 00Z ETA SURFACE TEMPERATURES AND MORE IN LINE WITH OBSERVED SURFACE TEMPERATURES ACROSS CWA. HAVE LOWERED MAXIMUMS FOR THIS AFTERNOON 3-5 DEGREES EXCEPT OVER SNOWLESS (SOUTHWESTERN) PORTIONS OF CWA. 12Z NGM AND ETA ARE SLOWER THAN CORRESPONDING 00Z RUNS IN TERMS OF UPSTREAM SHORTWAVE. ALTHOUGH 12Z NGM SUGGEST PRECIPITATION WILL BE IN ABOUT THE SAME AREA AS THE 00Z NGM...THE 12Z ETA AND NGM 400 MB POTENTIAL VORTICITY ADVECTION FIELDS ARE REMARKABLY SIMILAR...WITH A BULLSEYE OVER MSP FOR 18Z WED. HAVE BEEFED UP MENTION OF SNOW IN THE ZONES INCLUDING AND NEAR MSP FOR WEDNESDAY. PRELIMINARY THINKING IS SEVERAL INCHES WITH THE MAXIMUM VALUES CROSSING MSP. THIS BASED ON PRECIPITABLE WATER VALUES AND 8 MICROBARS PER SEC OF UPWARD MOTION (FOR 18Z WED FOR MSP ON BOTH 12Z ETA AND 12Z NGM). UNLIKE LAST WEDNESDAY...600 MB TEMPERATURES ARE COLDER THAN -17...SO DENDRITIC CRYSTAL GROWTH WILL NOT BE AS EFFICIENT WITH THIS SYSTEM AS IT WAS WITH LAST WEDNESDAY'S. .MSP...NONE. NAISTAT mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 250 AM CST TUE JAN 18 2000 MAIN FCST CHALLENGE IS PCPN CHCS AND TYPE LATER TNGT...ALTHOUGH WL HAVE TO DEAL WITH FOG/ST IN THE SHORT TERM. ON THE SYNOPTIC SCALE... MODELS ARE SIMILAR...ALTHOUGH ETA RMNS A LTL COOLER IN LOWER LEVELS WHICH MAKES PCPN TYPE A LTL DIFFICULT TO CALL. WL GENERALLY LEAN TWD ETA/AVN COMP. IN THE SHORT TERM...MID AND HIGH CLDS MOVG OVR ST/F HAS MADE IT HARD TO SEE IF E/SE CLRG IS CONTG. NRN SECTIONS OF THE LOW CLDS OVR NRN IA WERE CLRG SEWD EARLIER BUT THIS HAS SLOWED...SO WOULD EXPECT SWRN IA/EXTREME SERN NEBR HAS ALSO. IN ADDITION...WK SFC HIGH PARKED OVR SWRN IA AND WK SE FLOW OVR EXTREME SERN NEBR WAS KEEPING FOG WITHIN A COUNTY OR SO OF THE MO RIVER. SOME VSBYS WERE QUITE LOW...LESS THAN 1/2 MILE...ALTHOUGH MOST REPORTING SITES CONTD TO STAY UP. NLG PROFILER SHOWD A SLIGHT INCREASE IN LOW LVL WINDS AND LATEST RUC ALSO INCREASED A 925 MB NW WND. SO WL NOT ISSUE ADVSRY ATTM AND FOG SHOULD LIFT THIS MORNING. WL THOUGH TRIM BACK TEMPS A LTL ERN ZONES CLOSER TO FWC BECAUSE OF MORNING FOG/CLDS. MODELS ALL DEPICT A VORT MAX MOVG ACRS SRN NEBR/NRN KS VCNTY LATER TNGT IN MOIST PACIFIC UPR FLOW. MID AND HIGH LVL MOISTURE WL BE PLENTIFUL AND SOME INCREASE IN LOW LVL MSTR IS LIKELY AS WELL AS WNDS TURN TO SE. DECENT ISENTROPIC LIFT IN 295-300 K SFC LOWERS PRES COND DEFICITS TO LESS THAN 20 MB AND ALL MODELS GENERATE PCPN BY MORNING. WL INTRODUCE POPS AFT MIDNIGHT ALL ZONES...HIGHEST W... AND INCREASE THEM QUITE A BIT ON WED. 1000-850 VS 850-700 MB THICKNESS FCST FM ALL MODELS ATTM DOESN/T POINT TO FREEZING PCPN ALTHO THIS WL HAVE TO BE WATCHED. WL NOT CHANGE LOW FCST TOO MUCH ATTM...AND INCREASE IN CLDS LATER TNGT AND SE WNDS COULD CAUSE A SLIGHT RISE IN TEMPS TWD MORNING. ETA/AVN 1000-500 THICKNESS FCST SUGGESTS PCPN TYPE MAINLY S NERN ZONES ALTHO ETA FCST SOUNDINGS...WHICH ARE COOLER THAN NGM/AVN...LEANS TWD MAINLY SNOW ALL AREAS. THIS MAY BE A BIT TOO COOL GIVEN LAST NGTS 850 MB ANLYS. SO LEANING TWD AVN/ETA COMPROMISE...WL KEEP SOME RAIN OR RAIN SNOW MIX IN SRN 2/3RDS OF FCST AREA. STG COOL ADVCTN IN AFTN WOULD CHANGE ANY PCPN TO SNOW...ALTHO QG FORCING RAPIDLY SHIFTS E WITH DIVERGING Q VECTORS IN AFTN AND LTL OR NO LIFT FCST WITH SHRTWV/MAX DROPG OUT OF CAN RMNG TO OUR NE. WL KEEP IDEA OF WINDY AND COLDER IN THE AFTN BUT NOT MENTION FALLING TEMPS ATTM. WL TRIM BACK HIGHS A BIT BECAUSE OF CLDS/PCPN AND THE AFTN COOL ADVCTN. WL NOT CHANGE EXTENDED BASED ON LATEST MRF. .OMA...NONE CHERMOK ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 1019 AM EST TUE JAN 18 2000 LTST SFC ANALYSIS INDICATES FNTL BNDRY GETTING WAVY ACRS THE RGN... XTNDG JST E OF CHS THEN SW TO NBC...WNW TO N OF MCN THEN NW TWD ATL. LST GUD FIX ON LO WAS IN VCNTY OF NRN GA/SERN TN...THO ACTUAL POSN OF SFC LO NOW TUFF TO PICK OUT AS TRANSLATION TWD THE CST APPEARS TO BE OCCURING. WNDS ARE STARTNG TO BECOME CNTRCLOCKWISE JST E OF CHS...AND SFC TEMPS AT OGB/FLO/MYR HV ALL DECREASED IN THE PAST HR IN MORE NRLY FLO...AFT RISING FOR MOST OF THE NGT...WHILE FLO AT BUOY 41004 NOW SE. SHUD SEE SFC LO START TO APPEAR JST TO OUR E OVR NXT FEW HOURS. GUD SLUG OF MSTR ALNG AND N OF MCN TO NBC LINE HDNG SE ACRS CWA. WL NEED TO KP POPS UP THRU THE AFTN MOST FOR AREAS N OF SAV RVR...AND RAISE A LTL S OF SAV RVR. AS SFC LO DVLPS OFF THE CST THS AFTN...NE FLO ARND IT WL THROW SOME MSTR FM THE ATLNTC BACK ACRS THE AREA...AND CAUSE PCPN TO PERSIST INTO THE ERLY EVENING HOURS FOR MUCH OF THE RGN. DO NOT LIKE TO CHG 2ND PD OF FCST NORMALLY WITH MORNING UPDATE...BUT REALLY FEEL IT IS NECESSARY IN THIS CASE. WL ADD AT LST CHC POPS ALL CSTL AREAS WI WDLY SCT POPS WELL INLAND. BASED ON LTST RUC/MESOETA...WHICH SEEM TO HAVE GUD HANDLE ON SITN...DRIER AIR/SINKING MOTION REALLY DOES NOT GET ALL THE WAY THROUGH CWA UNTIL CDFNT PUSHES S OF SE GA LTR TNT. SO CLRNG SHUD STL OCCUR FM NW TO SE...BUT JST A LTL LATR THAN PREVSLY THOUGHT. CWF...WINDS OVER THE CSTL WATERS ARE ELY ACROSS THE N PTN AND S-SW ACROSS THE S. WINDS HV BEGUN TO INCREASE ACROSS GA WATERS AS EVIDENCED BY 41008. LOOKS LIKE 20 KT A GOOD BET THIS AFT ACROSS THE GA WATERS. WL RAISE FLAGS FOR THE NEAR SHORE WATERS. OVER THE SC WATERS...AS LOW PRES MOVES OFF THE CST THIS EVE AND INTENSIFIES...IT APPEARS AS THO SCA COND WL SET IN DURING THE EVE. WL THEREFORE RAISE FLAGS FOR THE SC WATERS THIS PKG. .CHS... SC...SMALL CRAFT ADVISORY SOUTH SANTEE RIVER TO SAVANNAH OUT 20 NM EXCLUDING THE CHS HARBOR. GA...SMALL CRAFT ADVISORY SAVANNAH TO ALTAMAHA SOUND OUT 60 NM. WOODWORTH/TJR sc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GREENVILLE-SPARTANBURG SC 1000 AM EST TUE JAN 18 2000 SO MUCH FOR MODEL QPF. THE MAIN CONCERN FOR THE MORNING UPDATE IS WHAT TO DO WITH THE WARNINGS/ADVISORIES THAT ARE CURRENTLY IN EFFECT. THE EVENT SEEMS TO BE WINDING DOWN SORT OF QUICKLY JUDGING BY KGSP RADAR...WHICH SHOWS MOST OF THE SIGNIFICANT PRECIPITATION MOVING OUT OF UPSTATE SC AT 1430Z. THE RADAR STILL SHOWS WIDELY SCATTERED PRECIP ELEMENTS ACROSS THE MOUNTAINS AND FOOTHILLS AND NO DOUBT THERE ARE AREAS OF FREEZING DRIZZLE ACROSS THE NC PIEDMONT...BUT AREA RADARS DO NOT SHOW ANY SIGNIFICANT PRECIP UPSTREAM. BOTH THE 06Z ETA AND THE 12Z RUC SHOW ALL THE LOW LEVEL FORCING FOR ADDITIONAL PRECIP ENDING IN THE 18Z TO 21Z TIME FRAME...EVEN THO THE 06Z ETA HOLDS ON TO SOME PRECIP THRU THE END OF THE DAY. WITH THAT IN MIND...DO NOT SEE MUCH OF A REASON TO HOLD ONTO THE WINTER WEATHER ADVISORIES ANY LONGER. WHILE THERE MAY BE SOME LINGERING FREEZING DRIZZLE IN THE WARNING AREA E OF THE MOUNTAINS... IT DOES NOT REALLY JUSTIFY HOLDING ONTO THE WARNING THERE AND WILL CANCEL IT. THE ONE AREA OF CONCERN MAY BE THE NORTHERN MOUNTAINS...WHERE VEERING LOW LEVEL FLOW WILL INTRODUCE MORE OF AN UPSLOPE COMPONENT AS THE DAY PROGRESSES AND 850 MB TEMPS MIGHT DIP SLIGHTLY. HOWEVER...MOISTURE IS ON THE WANE AND THE FORCING IS ALMOST ALL MECHANICAL. CALLS TO THE NORTHERN MOUNTAIN COUNTIES INDICATE THAT ANY PRECIP FALLING CURRENTLY IS LIQUID AND SURFACE TEMPS ARE ABOVE FREEZING. THUS...THE WARNING WILL BE CANCELLED THERE TOO. .GSP...NONE. MOORE sc NORTHEAST AND NORTH CENTRAL COLORADO AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER COLORADO 303 PM MST TUE JAN 18 2000 SHORT TERM DISCUSSION: CURRENT RADAR AND SATELLITE DATA SHOWING ANOTHER CHUNK OF ENERGY MOVING UP AND OVER THE UPPER RIDGE AXIS RIGHT INTO THE FORECAST AREA NOW. THE AREA PROFILERS AND RUC GRIDS ARE SHOWING A JET IN THE VICINITY AND SOME OF THE RADAR RETURNS APPEAR BANDED. REPORTS IN THE HIGH MOUNTAINS ALSO INDICATE THE WEST-SOUTHWESTERLY WINDS IN INCREASING NOW. RADAR DOES SHOW DECENT COVERAGE BUT MOST OF IT IS VIRGA OVER THE PLAINS...WITH JUST A FEW SPRINKLES. VERY LIGHT SNOW IN THE MOUNTAINS. CROSS SECTIONS SHOW CSI AROUND THROUGH THE ENTIRE FIRST PERIOD...WITH THE JET IN THE VICINITY...AND WEAK Q-G ASCENT TOO. THERE IS ALSO DECENT CONVECTIVE INSTABILITY ALL NIGHT AND STEEPER LAPSE RATES THEN AS OF LATE. STILL PRETTY WARM ALOFT THOUGH...AND THE WIND DIRECTION FOR GOOD OROGRAPHIC SNOWFALL IS NOT GREAT. WILL GO "LIKELY"S IN THE MOUNTAINS TONIGHT. CONSIDERING SNOW MODEL AND ABOVE INFORMATION...5 INCHES AT MOST IS POSSIBLE IN A FEW AREAS. SATELLITE PICTURES SHOW A BACK EDGE TO THE BEST MOISTURE AND MOISTURE GRIDS CONCUR... CLOUDINESS TO DECREASE GRADUALLY BY DAWN. LOW LEVEL SURFACE AND PRESSURE GRIDS SHOW TROUGH MOVING EASTWARD THIS EVENING OUT OF THE STATE BY MIDNIGHT KILLING THE DECENT SOUTHEAST FLOW. FOR THE PLAINS..."SCATTERED" LIGHT RAIN/SNOW SHOWERS LOOK OK OVER THE BEST MOISTURE FETCH/JET PROXIMITY AREAS (NORTHERN AND EASTERN BORDER ZONES)..."ISOLATED" REST OF PLAINS. TEMPERATURE/THICKNESS GRIDS SHOW LITTLE CHANGE IN LOWS TONIGHT FROM THIS MORNING'S LOWS. RJK LONG TERM DISCUSSION: UPR LV TROF WL CONT OVR ERN US AND OFF WRN US COAST THRU THU AS UPR LVL RDG REMAINS OVR GREAT BASIN. ON WED APPEARS QUITE A BIT OF MID-LVL DRYING WL OCCUR AS LARGE BATCH OF SUBTROPICAL MSTR MOVES EAST OF RGN ACCORDING TO CROSS-SECTIONS. QG FIELDS SHOW BASIC DESCENT ACRS RGN WITH POOR LAPSE RATES AND WRM MID-LVL TEMPS. THUS PCPN CHCS LOOK LOW EXCEPT FOR SOME WDLY SCT -SHSN OVR THE MTNS. LATEST CROSS-SECTIONS SHOW SOME POTENTIAL FOR HI WNDS EARLY WED MRNG IN THE HIGHER FOOTHILLS AS COMPONENT ALONG WNDS INCR TO 50KTS. OVER NERN CO MAIN CONCERN WL BE TIMING OF CDFNT INTO RGN. COULD SEE FNT MOVE INTO EXTREME NERN CO BY AFTN AND THEN BACKDOOR INTO FNT RANGE BY WED EVENING. AS A RESULT TEMPS FCSTS FOR WED AFTN WL BE TRICKY AS READINGS MAY TOP OUT BY MIDDAY IN THE NERN CORNER. FOR WED NGT AND THU COLD SFC HI PRES WL BUILD INTO NRN AND CNTRL PLAINS. THERE IS A BIG DISAGREEMENT IN THE MODELS REGARDING SFC POSITIONS AND PRESSURES BY 12Z THU. NGM AND AVN SHOW LEE TROF DVLP BY 12Z THU WITH LOW LVL FLOW BECOMING WLY OVR NERN CO AS SFC LOW PRES DVLPS OVR WY. MEANWHILE ETA HAS MUCH HIGHER SFC PRESSURES WITH LOW LVL FLOW MORE SELY. AT THIS TIME BELIEVE SHALLOW COLD AIRMASS WL REMAIN OVR NERN CO AND WL DISREGARD TEMP GUIDANCE FM FWC. BIG QUESTION IS WHETHER COLD AIR WL MAKE IT INTO THE FOOTHILLS. TEMPS IN THE FOOTHILLS COULD RANGE FROM THE 20S AND 30S TO THE 40S AND 50S. AS FAR AS PCPN GOES IF UPSLOPE IS STRONGER THAN FCST COULD SEE SOME LIGHT PCPN DVLP OVR NERN CO WED NGT AND THU. CROSS-SECTIONS DO SHOW SOME POTENTIAL FOR CONDITIONAL SYMMETRIC INSTABILITY (CSI) IF DEPTH OF MSTR IS SUFFICENT. IN THE MTNS COULD SEE SOME INCR IN SHSN ACTIVITY WED NGT AND THU AS OROGRAPHIC FLOW BECOMES MORE WNW. AVN AND ETA SHOW SOME MID-LVL CAA OVERNIGHT AND WITH UPR LVL JET IN PLACE PCPN COULD BE ENHANCED BY CSI. IN EXTENDED PD CLOSED UPR LVL LOW OFF WRN US COAST WL MOVE EAST AND SHEAR APART AS IT MOVES ACRS THE ROCKIES ON FRI. LAST NGT'S MRF SHOW SFC LOW OVR SERN WY ON FRI WITH DOWNSLOPE FLOW OVR NERN CO THUS TEMPS WOULD MDT SOME WITH LITTLE CHC FOR SNOW. HOWEVER KNOWING MRF'S BIAS FOR DVLPG SFC LOWS TO FAR N WL LEAVE FCST FOR FRI ALONE. IN THE MTNS STILL LOOKS LIKE A GOOD SHOT FOR SNOW AS ABV MENTIONED SYS MOVES ACRS RGN. FOR SAT AND SUN UPR LVL RDG WL REBUILD ACRS RGN WITH HI PRES AT THE SFC. THUS WL GO WITH A DRY FCST WITH SEASONAL TEMPS. KLEYLA DEN...NONE. co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 1115 AM CST TUE JAN 18 2000 VIS SATELLITE SHOWS A BREAK IN THE CLOUDS OVER THE KC METRO EDGING WEST INTO MOST OF ATCHISON/JEFFERSON COUNTIES. THIS TREND IS BEING HANDLED WELL BY THE RUC MODEL...AND BELIEVE THAT THE LOW CLOUDS AND FOG WILL CONTINUE TO LIFT THROUGH THE AFTERNOON. MID-LEVEL CLOUD COVERAGE OVER SOUTHEAST NEBRASKA ALSO APPEARS TO BE LESSENING...FOR THE MOST PART... AS IT MOVES SOUTHEASTWARD. WILL UPDATE ZONES SHORTLY AND PLAN ON USING PARTLY SUNNY WORDING OVER NORTH-CENTRAL KANSAS AND BECOMING PARTLY SUNNY OVER MUCH OF NORTHEAST AND EAST-CENTRAL KANSAS. MAY KEEP SOME THICKER CLOUD COVER OVER THE SOUTHEAST ZONES AND DO SOME RECONFIGURING OF GROUPINGS. WILL ALSO TAKE A GOOD LOOK AT TEMPERATURES BEFORE RELEASE TIME. 65/63 .TOP...NONE. ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 1045 AM EST TUE JAN 18 2000 INTENSITY AND AREAL COVERAGE OF SNOW ARE AGAIN INCREASING WITH THE APPROACH OF A SHORT WAVE DROPPING SE OUT OF ONTARIO LATE THIS MORNING. UPSTREAM AND LOCAL RADARS CLEARLY SHOW AN ENHANCED AREA OF 28+ DBZ WORKING ITS WAY SE TOWARD ERN UPR MI. LOCATION OF THIS AREA OF MODERATE TO HEAVY SNOW IS MATCHING WELL WITH ETA AND LATEST RUC SOLUTION...PIN-POINTING THE GREATEST AREA OF DPVA AND 850-700 MB Q-VECTOR CONVERGENCE OVER CENTRAL UPR MI ATTM. GREATEST UPPER SUPPORT SLIDES SE THROUGH ERN UPR MI AND FAR NRN/NE LOWER MI THIS AFTERNOON. WEAK ISENTROPIC ASCENT WILL ALSO LEND SOME SUPPORT TO SNOW OVER THESE AREAS THROUGH THE AFTERNOON...BUT MIXING RATIOS ARE AROUND 1 G/KG OR SO. THUS...ADDITIONAL ACCUMULATIONS WILL BE LIMITED TO 2 TO 3 INCHES FOR ERN UPR MI AND 1 TO 3 ACROSS FAR NRN AND NE LOWER MI ZONES. WILL ALSO HAVE TO INTRODUCE CATEGORICAL POPS FOR SE SECTIONS OF THE CWA AROUND GLADWIN AND OSC BASED ON LATEST RUC PROJECTIONS OF VORT TRACK AND CURRENT RADAR TRENDS...BUT WILL LIMIT ACCUMULATIONS TO AROUND AN INCH. DRIER MID LEVEL AIR AND LACK OF UPPER FORCING AS THE SHORT WAVE SLIDES E OF THE AREA WILL PRECLUDE SIGNIFICANT SNOW IN LOCATIONS W OF TVC TO HTL. WILL WORD AS SCT SHSN FOR THE AFTERNOON. HOWEVER...LACK OF MID LEVEL MOISTURE AND AMPLE LOW LEVEL MOISTURE WILL CONTINUE TO PRODUCE PATCHY FREEZING DRIZZLE IN THESE LOCATIONS AS WELL. WILL WORDING ACCORDINGLY. TEMPS HAVE BEEN SLOW TO WARM SO FAR...BUT UPSTREAM TEMPS HAVE WARMED NICELY INTO THE LOW TO MID 20S OVER WI WITH WAA. WILL KEEP HIGH TEMPS IN THE LOW TO MID 20S FOR THE AFTERNOON IN ANTICIPATION OF INCREASING WAA AHEAD OF THE COLD FRONT. WILL ALSO HAVE TO ADJUST WORDING OF WIND FORECAST TO ACCOUNT FOR LATEST TRENDS. .APX...NONE. EME mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NASHVILLE TN 245 AM CST TUE JAN 18 2000 FORECAST QUANDARIES: PCPN...CLOUD COVER...AND TEMPS. CURRENT AWOS/ASOS OBSERVATIONS...SATELLITE IMAGERY...AND REGIONAL MOSIAC RADAR DATA SHOWING WIDESPREAD LIGHT RAINFALL ACROSS NORTHERN CWA WITH SCATTERED AREAS ACROSS SOUTHERN PORTIONS. RAINFALL PATTERN REFLECTED IN LATEST SURFACE ANALYSIS SHOWING STATIONARY FRONT POSITIONED ACROSS THE CENTRAL MID STATE...LIGHT SURFACE WINDS...AND IFR CEILINGS PREDOMINATE.. RECENT RUC/UPPER LEVEL CHART ANALYSIS DEPICTING SHORTWAVES IN DEVELOPING NW FLOW...SATURATED LOW AND MID LEVELS...AND PROGRESSIVE MID AND UPPER LEVEL JET SUPPORT. 00Z TUE MODEL RUNS REGIONALLY SHOWING NO MAJOR DEVIATIONS IN RELATION TO EACH OTHER AT THE SURFACE OR ALOFT THROUGH 00Z THU. NW UPPER LEVEL FLOW EXPECTED THROUGH PERIOD WITH WEAK UPPER LEVEL TROUGH AND EMBEDDED SHORTWAVES MOVING EAST OF REGION BY 00Z WED. WEAK RIDGING PATTERN PROGGED TO DEVELOP THROUGH REMAINDER OF PERIOD. AT THE SURFACE... LOOK FOR LOW PRESSURE AND ASSOCIATED STATIONARY FRONT TO MOVE ALSO EAST OF AREA BY 00Z WED AS HIGH PRESSURE CURRENTLY OVER THE SOUTHWESTERN MOUNTAINS OF MONTANA MOVES SOUTHEASTWARD INTO THE REGION BY 12Z WED. LATEST NCEP MODEL DIAGNOSTIC/PROGNOSTIC DISCUSSIONS POINTING OUT THAT AVN HAS BEEN THE MOST CONSISTENT OF THE MODEL RUNS AS OF LATE. HAVE NO REASON TO DISPUTE THIS REGIONALLY...AND WILL LEAN TOWARD THIS SOLUTION. TODAY...FORECAST QUANDRY DURING THIS TIME PERIOD CENTERS AROUND TIMING OF PRECIPITATION ENDING AND POSSIBLE BREAKAGE IN CLOUD COVER DURING THE AFTERNOON. AVN RH PROGS SHOWING A DRYING TREND IN MID LEVELS BY 18Z OVER NW PORTIONS OF CWA AND SPREADING SOUTHEASTWARD ACROSS ENTIRE REGION BY 00Z WED. WILL GO IN LINE WITH PREVIOUS ZONE ISSUANCE ON PARTIAL CLEARING WEST AND CENTRAL AFTERNOON WITH LATE AFTERNOON EAST. AVN POPS ARE WIDELY SCATTERED BNA BY 12Z TUE. WITH CURRENT REGIONAL RADAR MOSIAC TRENDS...BELIEVE THIS IS APPROPRIATE FOR WESTERN AND CENTRAL PORTIONS DURING THE MORNING HOURS WITH SCATTERED POPS CONTINUING OVER THE EAST. TONIGHT...A CONTINUED DECREASE IN LOW AND MID LEVEL CLOUDINESS EXPECTED OVER EASTERN HALF OF REGION. MID AND UPPER LEVEL MOISTURE ADVECTION ASSOCIATED WITH A BROAD CENTRAL U.S. VORTICITY PATTERN PROGGED OVER WESTERN HALF OF REGION BY 12Z WED. WILL GO PARTLY CLOUDY SKIES EASTERN HALF WITH MOSTLY CLOUDY REMAINDER. WEDNESDAY...ANY ADDITIONAL "CLEARING" IN SKY CONDITIONS WILL BE "SHORT LIVED" AS SURFACE FRONT DEVELOPS ACROSS THE MISSISSIPPI VALLEY WITH SHORTWAVES IN THE UPPER LEVEL FLOW BECOMING MORE PREDOMINATE. WILL GO WITH BKN SKY CONDITIONS THROUGH 00Z THU AS BEST PCPN CHANCES REMAIN TO OUR SOUTH. TEMPERATURES...WITH PARTIAL CLEARING THIS AFTERNOON EXPECTED... WILL GO A FEW DEGREES ABOVE AVN FAN HIGHS AND MORE IN LINE WITH NGM BOUNDRY LAYER TEMPERATURE SCHEME VALUES. TONIGHT LOWS DEPEND ON AMOUNT OF CLOUD COVER ERODING. FAN AVN HANDLES THIS SCENARIO ADEQUATELY. WITH SOUTHERLY WIND FLOW DEVELOPING..WILL TREND TOWARD AVN FAN HIGHS FOR WEDNESDAY. PRELIMINARY NUMBERS FOR COORDINATION PURPOSES ONLY... BNA 050/035/052/034 2013 CSV 048/031/050/030 3013 .BNA...NONE. $$ 14 JBW tn